Means for variably controlling electrical instruments



Feb. 7, 1928. 1,658,427

A. D. CARDWELL MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS Filed Oct. 22, 1924 2 Sheets-Sheet 1 INVENTOR [if/w? fi. (Ya/dwell Q Q G w L Feb. 7, 1928.

1,658,427 A. D. CARDWELL MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS Filed Oct. 22. 1924 2 Sheets-Sheet 2 INVENTOR BY 5'- 998mm ATTORNEY Patented Feb. 7, 1928'.

UNITED STATES ALLEN D. CARDWELL, F ROGKVILLE CENTER, NEW YORK.

MEANS FOR VARIABLY CONTROLLING ELECTRICAL INSTRUMENTS.

Application filed October 22, 1924. Serial No. 745,176.

Sonic electrical instruments are provided with members or elements that are movable with relation to other complemental members or elements thereof, and such movable members or elements are frequently adjusted to various positions according to the requirements or desired results to be attained. Among instruments of the class specified are variable air condensers, variometers. variocouplers and rheostats. .Vhere such instruments are used in the radio art it is desirable to be able to adjust the movable member or element readily and with a degree of fineness according to requirements desired. It has been customary to provide the said movable members with dials having graduations thereon, and such dials have frequently been operated in conjunction with a Vernier device to permit relatively minute adjustments of the movable element or member. Ordinarily variable condensers have been constructed with semi-circular movable plates so that there is a uniform variation of capacity for uniform angular variation.

Said plates will give a maximum capacity for a given over-all area of condenser, inasmuch as the full radii at all points of the rotor plates are effective. Condensers with other than semi-circular plates have been used, as where thewave length scale is to be uniform, or where the variation in kilocycles or frequencies is to be uniform, or where it is desired to have a definite change in percentage, such as in decremeters, or the shape of the plates has been designed particularly to produce what is called a logarithmic variation of capacity.

The object of my invention is to provide means for operating the rotary element or member. of an instrument of the character specified, from an operating member, Whereby the latter may be given a uniform movement of constant character. or of equal changes or distances. and the said movable element or member will be moved thereby in a more or less variable manner respecting said uniform movement of said member in such a Way as to affect the circuit controlled in a predetermined manner, according to the character of the instrument, whether it be a condenser, a variometer. a vario-coupler, or a rheostat, or, in other words, whether the instrument is adapted to have its capacity changed, its inductance changed, its electro-magnetic coupling or its resistance changed, or a combination of any two or more of these.

With my improvement embodied in a variable air condenser I am enabled to provide such a condenser having semi-circular plates, or substantially so, commonly called a straight line capacity condenser, whereby I can produce with such a condenser from and in conformity with a uniform movement of the controlling member or dial changes in the capacity constants of the circuit to conform with a uniform wave length variation of the circuit, or to conform with a uniform frequency variation of the circuit, or to ponform with a uniform logarithmic change in the circuit, the same as though condensers had been made with plates so shaped as to respectively produce either of said results. The same characteristics apply to the control of a variable inductance, such a variometer, variable couplers, such as vario-couplers. and a variable resistance, such as a rheostat.

In the accompanying drawings I have illustrated a controlling gearing connected with the movable element or member of an electrical instrument whose electrical constants are to be varied or changed by the uniform operation of a controlling member or dial, whereby such movable element or member may be operated variably or nonuniformly by said uniform operation of the controlling member in accordance with the desired results to be attained. The condenser I have illustrated (in conjunction with my improvement) having the so-called semi-circular rotor plates may be operated in such a manner that a very small angular movement of the condenser shaft will be caused by a relatively large movement of the controlling shaft when the condenser is at or near its minimum capacity point, and an increased movement of the rotor plates relative to the driving or controlling member will be caused as the rotor plates advance toward or approach maximum capacity position. This change from a large gear ratio to a smaller ratio should be in accordance with the law which governs the wave length of the circuit by a change in capacity. To

be specific, the variation in wave length of a circuit is in accordance with the square ofthe capacity variation, so that a uniform variation of the controlling member will cause a variation in capacity in proportion to the square of the angle of rotation of the controlling member. mechanism is also applicable to a variometer, in that the rotary member thereof will be variably moved in an increasing ratio from its position of minimum inductance to its position of maximum inductance. If the character of the condenser or variometer or of the circuit requirements is such that it would require a uniform movement of the rotor shaft for a distance the same can be accomplished by having the contour of the pitch line of the intermeshing gears constant for any desired distance while other portions of such pitch line will produce a variable or non-uniform movement in the rotor or rotary element shaft from a constant movement of the controlling member or dial.

My invention also comprises novel details of improvement that will be more fully hereinafter set forth and then pointed out in the claims.

Reference is to be had to the accompanying drawings forming a part hereof, wherein Fig. l is a lan view of a variable air condenser emb ying my invention;

Fig. 2 is a partly sectional side view of Fig. 1; v

Fig. 3 is a plan view illustrating my imprpivements in connection with a variometer; an

Fig. etis a partly sectional side view of Fig. 3.

Similar numerals of reference indicate corresponding parts in the several views.

The condenser 1 may be of any suitable or usual construction, and is shown comprising a stator element or member having spaced stationary plates 2, and a complemental rotor element or member having spaced plates 3 carried by a rotative shaft 4 journaled in end plates 5 of the condenser frame, whereby when the rotor element is rotated with respect to the stator the capacity of the condenser will be varied in a well -known way. The variometer 6 may be of any suitable or usual construction, the same being shown comprislng an msulating element or member (-3 having suitable insulated wire windings 6', within which is located the complemental movable member or element 7 having insulated wire windings 7 of any suitable or usual construction. The element or member 7 is supported by shaft 8 to rotate within. element 6. The condenser and the variometer may be supported upon a panel board or other suitable support 9 in any suitable or well known way, as by means of one or more projections 10, which parts may be connected together by screws.

At 11, 12 my improved means is illustrated for operating the rotary element or member of the condenser or variometer from a uni- My improved gear 1 member be stationary or rotative.

secured to the shaft 4 of the con enser, or

to the shaft 8 of the variometer, or to the corresponding shaft of a rheostat, vario-coupler or other electrical instrument having a rotative element or member to be moved or adjusted with relation, to another or complemental member, whether the last named In the form shown in Figs. 1 and 2 the plate 5 of the condenser is extended beyond the main condenser frame a suitable distance and provided with a bearing 15 in which a shaft 16 is journaled and secured to the gear 12 by means of a pin 17. The gear 12 is shown provided with a hub or extension 18 receiving the internal bore 13 of the controlling member or dial 13, a set screw at 19 carried by the member 13 engaging the hub 18 for securing the member or dial 13 to the gear 12 for controlling the operation of the latter. In the form shown in Figs. 3 and -l the shaft 16 is supported by hearing 15 attached to panel or support 9 by screws 20 independent of the frame of the variometer,

The gears 11 and 12, as illustrated, are of the variety known as lobed gears, having cooperative teeth 11, 12 adapted to mesh in all cooperative positions of the gears. The particular contour of the gears at their respective toothed portions or pitch lines may be of any desired outline or configuration to produce the desired rotation of the movable element of the instrument effected from a uniform or constant rotation of the controlling or driving member 13.

The gear 11, as illustrated, has the shaft 4 eccentrically disposed, the curve of the toothed periphery or pitchvline of the gear being in the nature of a spiral. The periphery of the toothed portion or pitch line of gear 12 is of such a character as to gradually increase from a point 12 on one side of the axis of the gear, curving thence around the gear and terminating at a point 12 more distant from the axis of the gear than the point 12*. but on the same side of the said axis as the point 12". The gear teeth 11, 12 will be cut in such a manner that they will cooperate at all me hing points of the circumference of the periphery of the gears; and the length of the row of teeth 11 of gear 11 at the pitch line is the same as the length of the pitch line of the row of teeth 12 of the gear 12.

In the example illustrated the operative relation of gear 12 and gear 11 is such that for a substantially complete rotation of gear 12 in a direction from the position shown in liacordance with'the configuration or lay-out of the toothed contour of each gear. Such arrangement enables the graduations on the dial to indicate 360-instead of180 as is customary with the dials in radio receiving'and transmitting sets. The arrangement disclosed is such that the teeth of the longer .radius of the gear 11 mesh with the teeth of the shorter radius ofthe gear 12, as at the zero position of the dial. Since the gear 12 has a toothed periphery of different contour or outline from the toothed periphery of gear '11, it follows that when gear 12 is rotated in the direction of the arrow in Fig. 1 the gear 11, hence the shaft and element connected therewith, will be rotated relatively slowly with respect to a uniform distance of rotation of gear 12, and the relation of rotation of gear 11 by gear 12 from the last named point of engagement of the teeth of said gear, in the direction of said arrow, to the point of termination of rotation of said gears, as illustrated in Fig. 3, will cause the gear, 11, hence the element operated thereby, to be rotated at such a speed or distance traversed that said element will move in a variable manner, according to the illustration, with respect to its complemental member, such as the stator plates of a condenser, the

stationary winding of a variometer, the

winding or spaced contacts, or the contact arm, of a rheostat, (Whichever of the latter be the rotary or movable element), or the rotative winding of a vario-coupler or other electrical instrument heretofore specified. Upon the reverse rotation of gear 12, in the direction of the arrow in Fig. 3), the gear 12 and the element or member operated thereby will be rotated reversely and in inverse relation to its rotation last described. For eXample,-assuming that the elements of the electrical instrument are in the so-called zero position, such as with the plates of the rotor of a condenser out, or nearly out, of

' relation to the stator plates, or the rotary element of a variometer in the initial position respecting the stationary element 6, as illustrated in Fig. 4,'auniform rotation of gear 12, as for adistance between two graduations on the dial, will cause a relatively small movement of the movable element of the electrical instrument with respect to its stationary element-, and another such movement ofgear 12, as between the next ad acent graduations on the dial, will cause the same or a greater orspeedier movement ot the rotative element of the instrument and so on throughout the range of rotation in a given direction of such rotative element. Such movements of the rotative element may be increased in a desired ratio respecting a uniform rotation of gear '12, (or may be caused to be equal, or substantially equal, to the last named rotation for any given distance desired). As the movable element of the instrument enters or is displaced more or less with respect to the stationary element in the direction of greater capacity of the condenser, greater inductance of the variometer or vario-coupler, or greater resistance of the rheostat, the movement of the rotary element with respect to an adjustment or rota tion of gear 12 or the dial may increase, such as in proportion to various laws controlling wave length or frequency of a radio or other electrical circuit, either for reception or transmission of electrical waves, so that the selection of the desired wave length may be readily accomplished at all settings of the rotative elementof the instrument by means of a relatively coarse movement of the con trolling or operating'member, such as the dial,

While the gears 11, 12, as illustrated, are adapted to cause substantially 180 rotation of the movable element of the instrument for 360 rotation of the dial, it will be understood-that such ratio may be changed to accommodate any requirements of the instrument, by varying the length of the cooperative pitch lines. Although I have shown external cooperative gear teeth it will be understood that the gearing or transmission means between the controlling member or dial and the rotary element of the instrument may be internal gear mechanism, a friction drive or a flexible band and pulleys.

Having now described my invention what I claim is:

1. An electrical instrument of the class comprising relatively movable elements for producing variations of the constants of an electrical circuit, a controlling member, and gearing operatively connecting the controlling member with the movable element for imparting variable movements to the latter from equal extent of movement of the controlling member to produce equal changes in the electrical circuit in which the instrument is used.

2. An electrical instrument comprising a stationary element, another element rotatlve with relation to the stationary element for producing variations of the constants of an electrical circuit, a controlling member, and a plurality of gears having different cooperative pitch lines for imparting to the rotative element variation of angular movement withv respect to the stationary element from equal extent of movement of the controlling member to produce equal changes in the electrical circuit in which the instrument is used.

3. An electrical instrument comprisin a stationary element. another element rotatlve with relation to the stationary element for Ion the electrical producing variations of the constants of an electrical circuit. a controlling member, and aplurality of lobed gears connecting the controlling member with the rotative element, said gears having diiierent pitch lines for imparting variable movements to the rotative element derived from equal incre-V ments in the uniform movement of the controlling member to produce equal changes in circuit in which the instrument is used. i

4. An electrical instrument comprising a stationary element. another element rotative With relation to the stationary element for producing variations of the constants of an electrical circuit, a controlling member. and intermeshing lobed gears connected respectively with the rotative element and with the controlling member, the pitch line of one of said gears terminating on opposite sides of its axis and the pitch line of the other gear terminating in spaced relation on one side of its axis, with the termination of one end of the pitch line nearer said axis than the other termination of the pitch line, said pitch line extending substantially around said axis for imparting variations in angular rotation to the rotative element derived from equal increments in the rotation of the controlling member to produce equal changes in the electrical circuit in which the instrument is used.

5. A variable air condenser including a stationary element, a rotative element, a gear connected with the rotative element, and a tion on the same side ot the axis of said second named gear, said teeth extending substantially around said axis for imparting variation of angular movement of the rotative element with respect to the stationary element.

7. An electrical instrument comprising a stationary element. another element rotative with relation to the stationarv element, a controlling member, and gearing connecting the controlling member with the rotative element, said gearing having diiterent contours to impart variable rotation to the rotative element derived from uniform rotation ot the controlling member for changing the constants of the circuit in conformity with the movement of the controlling memher in such a manner that equal movements at the control member give equal changes in the resonant frequency of the circuit in which the electrical instrument is used.

' ALLEN D. GARDWELL. 

